Showing papers by "Volga State University of Water Transport published in 2016"
TL;DR: The dynamics, that governs the bistability of the phase shifts, is described by a driven pendulum equation and the implications of these stability results to the stability of chimeras are discussed.
Abstract: We study the co-existence of stable patterns of synchrony in two coupled populations of identical Kuramoto oscillators with inertia. The two populations have different sizes and can split into two clusters where the oscillators synchronize within a cluster while there is a phase shift between the dynamics of the two clusters. Due to the presence of inertia, which increases the dimensionality of the oscillator dynamics, this phase shift can oscillate, inducing a breathing cluster pattern. We derive analytical conditions for the co-existence of stable two-cluster patterns with constant and oscillating phase shifts. We demonstrate that the dynamics, that governs the bistability of the phase shifts, is described by a driven pendulum equation. We also discuss the implications of our stability results to the stability of chimeras.
59 citations
Posted Content•
TL;DR: In this paper, the authors developed foot force models of pedestrians' response to bridge motion and detailed, yet analytically tractable models of crowd phase-locking to investigate to what degree pedestrian synchrony must be present for a bridge to wobble significantly and what is a critical crowd size.
Abstract: Modern pedestrian and suspension bridges are designed using industry-standard packages, yet disastrous resonant vibrations are observed, necessitating multi-million dollar repairs. Recent examples include pedestrian induced vibrations during the openings of the Solferino Bridge in Paris in 1999 and the increased bouncing of the Squibb Park Bridge in Brooklyn in 2014. The most prominent example of an unstable lively bridge is the London Millennium Bridge which started wobbling as a result of pedestrian-bridge interactions. Pedestrian phase-locking due to footstep phase adjustment, is suspected to be the main cause of its large lateral vibrations; however, its role in the initiation of wobbling was debated. In this paper, we develop foot force models of pedestrians' response to bridge motion and detailed, yet analytically tractable models of crowd phase-locking. We use bio-mechanically inspired models of crowd lateral movement to investigate to what degree pedestrian synchrony must be present for a bridge to wobble significantly and what is a critical crowd size. Our results can be used as a safety guideline for designing pedestrian bridges or limiting the maximum occupancy of an existing bridge. The pedestrian models can be used as "crash test dummies" when numerically probing a specific bridge design. This is particularly important because the US code for designing pedestrian bridges does not contain explicit guidelines that account for the collective pedestrian behavior.
12 citations
TL;DR: In this article, a C-range horn antenna made of a graphene-containing carbon-based composite material has been developed, which is capable of efficiently operating in the C range frequency and possesses almost the same electrodynamic characteristics as the conventional metal antenna.
Abstract: Abstract C-range horn antenna made of a graphene-containing carbon-based composite material has been developed. Electrodynamic characteristics of the developed antenna and the identical metal antenna have been measured in the frequency range of 4.6–4.9 GHz. We have created two prototypes of horn antennas made of (i) carbon fiber and (ii) carbon fabric. It has been shown that the horn antenna made of graphene-containing composite material is capable of efficiently operating in the C-range frequency and possesses almost the same electrodynamic characteristics as the conventional metal antenna of the same geometry and size. However, the carbon-based antenna has enhanced stability in the wide range of temperatures to compare with the corresponding metal antenna.
7 citations
01 Aug 2016
TL;DR: In this paper, the authors presented a module-based microscopy system which provides an opportunity to looking for new applications of this setup depending on laboratories needs using with galvo and resonant scanners.
Abstract: This work represents the real steps to development and design advanced two-photon microscope by efforts of laboratory staff. Self-developed microscopy system provides possibility to service it and modify the structure of microscope depending on highly specialized experimental design and scientific goals. We are presenting here module-based microscopy system which provides an opportunity to looking for new applications of this setup depending on laboratories needs using with galvo and resonant scanners.
1 citations
01 Jan 2016
TL;DR: In this article, a self-developed two-photon laser scanning microscopy system for neuroscience has been presented, which allows to obtain 3D images of tissues due to laser focus change, that is possible due to substantially greater penetration depth on the main wavelength into biological tissues.
Abstract: One of the main visualization method in neuroscience is two-photon microscopy. However, scientists need to upgrade their microscopy system so regular because they are interested to get more specific data. Also this is due to the fact that this technique allows to obtain 3D images of tissues due to laser focus change, that is possible due to substantially greater penetration depth on the main wavelength into biological tissues. Self-developed microscopy system allow to modify the construction of microscope in not-complicated manner depending on specialized experimental models and scientific tasks. This work is small attempt to help researchers who are interested to build their own two-photon laser scanning microscope for using in neuroscience. The work was performed with financial support of the government represented by the Ministry of Education and Science of the Russian Federation, the unique identifier of the project is RFMEFI57814X0079, the agreement on granting a subsidy №14.578.21.0079 dated 28.11.2014.
1 citations
TL;DR: This work considers a system where servicing of a collection of stationary objects distributed inside a one-dimensional zone is done by a moving processor, and proposes algorithms based on dynamic programming for the resulting optimization problems.
Abstract: We consider a system where servicing of a collection of stationary objects distributed inside a one-dimensional zone is done by a moving processor. One-time servicing of each object must be performed during two runs of the processor, direct and reverse. Servicing of any object cannot begin before a predefined time moment; each object is also associated with an individual penalty which is a monotone increasing function of the moment when servicing ends. For the resulting optimization problems, we propose algorithms based on dynamic programming, give examples of their implementation, show results of numerical experiments; we study the computational complexity of these algorithms and the problems themselves.
1 citations
TL;DR: In this paper, the results of numerically modeling fatigue damage accumulation in heat-resistant alloys (Nimonic 80A, Haynes 188) under combined thermal mechanical loading are presented.
Abstract: The results of numerically modeling fatigue damage accumulation in heat-resistant alloys (Nimonic 80A, Haynes 188) under combined thermal mechanical loading are presented. Special attention is paid to the issues of modeling the processes of cyclic thermal plastic deformation and fatigue damage accumulation for complex deformation processes accompanied by the rotation of the main sites of stress and strain tensors.
TL;DR: In this paper, a mathematical model of damage accumulation processes in structural steels is developed, which considers degradation mechanisms that combine fatigue and creep of the material, and the reliability of chosen defining equations describing combined effect of fatigue and Creep mechanisms is confirmed.
Abstract: A mathematical model of damage accumulation processes in structural steels is developed. This model considers degradation mechanisms that combine fatigue and creep of the material. The processes of viscoplastic deformation and damage accumulation in 08Х18Н10Т and 12Х18Н9 structural steels are numerically studied. The numerical results are compared with the data from full-scale experiments. The reliability of chosen defining equations describing combined effect of fatigue and creep mechanisms is confirmed.